DTC P1133 O2S Insufficient Switching Sensor 1. Chevrolet PJJ 2000

For 1990-2009 cars
Engine Controls Components
Oxygen Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM continuously monitors the oxygen sensor 1 (O2S 1) activity for 100 seconds. During the monitor period, the PCM counts the number of times that the O2S 1 switches from rich to lean and from lean to rich. You can determine a total for all of the switches with this information. If the number of switches is too low, a DTC P1133 will set.

### Conditions For Running The DTC

• | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set.

• | The engine coolant temperature (ECT) is more than 75°C (167°F).

• | The engine speed is between 1800 RPM and 2300 RPM.

• | The engine is operating in closed loop.

• | The throttle position (TP) angle is between 8 percent and 15 percent.

• | The evaporative emissions control system is commanded open for more than 80 percent.

• | The purge learned memory is more than approximately 0.86.

• | The diagnostic completes when 30 seconds of accumulated time has been spent in the above conditions.

### Conditions for Setting the DTC

The number of rich to lean counts is less than 1 or the lean to rich counts is less than 1.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present.

• | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

• | A history DTC stores.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | Use a scan tool to clear the DTCs.

### Diagnostic Aids

DTC P1133 is most likely caused by one of the following:

• | Fuel pressure--The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0172 will be set. Refer to Fuel System Diagnosis .

• | Leaking injector--A leaking or malfunctioning injector can cause the system to go rich.

• | MAP sensor--An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected.

• | Pressure regulator--Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.

• | TP sensor--An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.

• | O2S 1 contamination--Inspect O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure.

#### DTC P1133-Oxygen Sensor (O2S) Insufficient Switching (Sensor 1)

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn ON the ignition switch leaving the engine OFF.
2. Install a scan tool.

Are any component DTCs set?

--

Go to the applicable DTC table

Go to Step 3

3

1. Start the engine.
2. Idle the engine at the normal operating temperature.
3. Operate the vehicle within the Conditions for Running this DTC as specified in the supporting text.

Important:: The vehicle must be operated within the Conditions for Running the DTc in order for the Rich/Lean and Lean/Rich Transition Data to become active. If not the scan tool will display 0 counts.

4. Monitor the Lean/Rich Transition and Rich/Lean Transitions while recording the number of switches.

Does the parameters show fewer transitions than the specified values?

1-1

Go to Step 4

Go to Step 17

4

1. Turn OFF the ignition.
2. Visually/physically inspect the following items:

• | inspect to see that the O2S 1 is securely installed.

• | Inspect for corrosion on the terminals.

• | Inspect for terminal tension at the following connections:

- | O2S 1 electrical connector

- | PCM electrical connector

• | Inspect the O2S 1 ground circuit for a good connection.

• | Inspect for any damaged wiring.

Was a problem present in any of the above areas?

--

Go to Step 9

Go to Step 5

5

1. Start the engine.

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

2. Inspect the exhaust manifold for an exhaust leak near the engine
3. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 3

Go to Step 6

6

1. Turn OFF the ignition.
2. Disconnect the O2S 1 electrical connector at the sensor.
3. Turn ON the ignition, with the engine OFF.

Does the scan tool voltage indicate the O2S 1 voltage within the specified value?

407-509 mV

Go to Step 7

Go to Step 10

7 | Connect a jumper wire between the O2S 1 high circuit (PCM side) signal circuit to ground. Does the scan tool voltage indicate that the O2S 1 voltage is below the specified value? | 200 mV | Go to Step 8 | Go to Step 11

8

1. Turn OFF the ignition.

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

2. Replace the Oxygen Sensor (O2S 1). Refer to Oxygen Sensor Replacement .

Notice: Determine and correct the cause of the contamination in order to prevent damage to the replacement sensors.

• | Fuel contamination

• | Use of improper RTV sealant

• | Engine oil/coolant consumption

Did you complete the replacement?

--

Go to Step 17

--

9 | Repair the condition as necessary. Did you complete repair? | -- | Go to Step 17 | --

10

1. Turn OFF the ignition.
2. Repair the O2S 1 signal circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

--

11

1. Remove the jumper wire.
2. Measure the voltage between the O2S 1 high signal circuit and ground using a DMM.

Does the O2S 1 voltage measure above the specified value?

407 mV

Go to Step 12

Go to Step 13

12

1. Turn OFF the ignition.
2. Disconnect the PCM electrical connectors.
3. Test the O2S 1 low circuit for continuity.
4. If the O2S 1 low circuit measures over the specified value, repair the following conditions:

• | Open circuit

• | Poor connector

Did you complete a repair?

5ohms

Go to Step 17

Go to Step 14

13

1. Turn OFF the ignition.
2. Disconnect the PCM electrical connectors.
3. Test the O2S 1 signal circuit for continuity.
4. If the O2S 1 low circuit measures over the specified value , repair the following conditions:

• | Open circuit

• | Poor electrical terminal connection

Did you complete a repair?

5ohms

Go to Step 17

Go to Step 15

14

1. Inspect the O2S 1 low circuit for a poor connection at the PCM.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

15

1. Inspect the O2S 1 signal circuit for a poor connection at the PCM.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

16 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | --

17

1. Use a scan tool to clear the DTCs.
2. Operate the vehicle within the Conditions for Running this DTC as specified in the supporting text.

Does the DTc reset?

--

Go to Step 2

System OK